Not applicable.
Not applicable.
1. Field of the Invention
The present invention relates generally to a piezoelectric identification device and applications thereof. More particularly, it relates to a piezoelectric device for obtaining biometric information, such as a fingerprint, and using the obtained information to recognize and/or identify an individual.
2. Background Art
Biometrics are a group of technologies that provide a high level of security. Fingerprint capture and recognition is an important biometric technology. Law enforcement, banking, voting, and other industries increasingly rely upon fingerprints as a biometric to recognize or verify identity. See, Biometrics Explained, v. 2.0, G. Roethenbaugh, International Computer Society Assn. Carlisle, Pa. 1998, pages 1-34 (incorporated herein by reference in its entirety).
Optical fingerprint scanners are available which detect a reflected optical image of a fingerprint. To capture a quality image at a sufficiently high resolution, optical fingerprint scanners require at minimum optical components (e.g., lenses), an illumination source, and an imaging camera. Such components add to the overall cost of a fingerprint scanner. Mechanical structures to maintain alignment also increase manufacturing and maintenance costs.
Solid-state silicon-based transducers are also available in fingerprint scanners sold commercially. Such silicon transducers measure capacitance. This requires the brittle silicon transducers to be within a few microns of the fingerprint sensing circuit reducing their durability. To detect a rolled fingerprint, the sensing array of the solid-state transducer needs to have an area of 1 inchxc3x971 inch and a thickness of about 50 microns. This is a big geometry for silicon that increases the base cost of a fingerprint scanner and leads to greater maintenance costs. Durability and structural integrity are also more likely to suffer in such a large silicon geometry.
What is needed is an inexpensive, durable fingerprint scanner with low maintenance costs. What is also needed is a low cost biometric device that can protect the individuals and the general populace against physical danger, fraud, and theft (especially in the realm of electronic commerce).
The invention provides a device, system, and method for obtaining biometric data from a biological object. In accordance with the invention, a biological object (e.g., a finger or hand) is placed proximate to a piezoelectric sensor, and the sensor is operated to obtain an output. This output is then processed to produce the biometric data. For example, a device according to the invention can capturing a fingerprint, form a three-dimensional map of a finger bone, and/or determine the direction and speed of arteriole and/or capillary blood flow in a finger.
In accordance with the invention, a piezoelectric sensor array is used to obtain the biometric data. In one embodiment, a piezo ceramic sensory array is used to obtain the data. In another embodiment, a multi-layer sensor array structure having a PVDF of a piezo ceramic layer in between two conductor grids orthogonal to one another is used to obtain the data. Urethane can be added to one side of the senor array where, for example, a finger is placed. A foam substrate can be used as a support. Multiplexers according to the invention are switched to control the sensor array.
In an embodiment, the invention comprises a piezoelectric sensor, and a processor, coupled to the sensor, that receives an input from the sensor and produces biometric data. Devices and/or systems according to embodiments of the invention are capable operating in one or more modes to obtain a variety of biometric data. These operating modes include an impedance detection mode, a voltage detection mode, an ultrasonic transmission and echo detection mode, an imaging mode, and a Doppler-shift detection mode. The presence of a fingerprint on a sensor according to the invention can be used to turn-on a device. A single pixel or a group of pixels can then be detected and readout to a memory.
It is a feature of the invention that embodiments can be used to recognize and/or verify the identity of individuals.
It is a feature of this invention that it can operate as part of a personal area network, using a xe2x80x9cpublic service layerxe2x80x9d according to the invention.
It is another feature of the invention that embodiments can be used to control and/or restrict access.
A further feature of the invention is that embodiments can be used as an electronic signature device.
Further features and advantages of the present invention, as well as the structure and operation of various embodiments of the present invention, are described in detail below with reference to the accompanying drawings.